Free uptime monitoring is a crowded market. The catch is that every free plan has different limitations, and the limitations that matter depend entirely on what you're monitoring and how you need to be alerted.
Here's an honest comparison of every meaningful free uptime monitoring plan in 2026.
UptimeRobot Free
Monitors: 50 Check interval: 5 minutes (fixed) Alert channels: Email only (no WhatsApp, Telegram, or Slack on free) History: 3 months Commercial use: ❌ Banned since October 2024 Status page: 1 basic page (UptimeRobot branding)
The most generous free tier by monitor count. The 5-minute interval means a worst-case 5-minute detection gap. The commercial use ban is the critical catch: if you're using it to monitor client sites or a revenue-generating product, you're technically in violation of their Terms of Service.
Best for: Personal projects, non-commercial experimentation.
Better Stack (Better Uptime) Free
Monitors: 10 Check interval: 30 seconds Alert channels: Email and Slack History: 30 days Commercial use: ✅ Status page: 1 page
Good free tier with fast 30-second checks, but limited to 10 monitors. No WhatsApp or Telegram.
Best for: Small teams using Slack as their primary alert channel who need fast checks on a handful of services.
HetrixTools Free
Monitors: 15 Check interval: 1 minute Alert channels: Email only on free History: 14 days Commercial use: ✅ (requires login every 90 days to keep account active) Status page: Unlimited basic pages
Solid free tier. 1-minute intervals are better than UptimeRobot's 5. The "login every 90 days" condition to maintain active status is unusual — accounts that go 90 days without login are automatically paused.
Best for: Developers who are active in the tool and want 1-minute checks for free.
ndelog Sentinel Spark (Free)
Monitors: 15 HTTP + 1 each of heartbeat, SSL, domain Check interval: 5 minutes Alert channels: Email (1 address) + 5 WhatsApp msgs/month + 5 Telegram msgs/month History: 7 days Commercial use: ✅ Status page: 1 page (ndelog branded) Push notifications: Unlimited (mobile app)
Smaller monitor count than UptimeRobot. The distinguishing feature is that it's the only free plan offering any WhatsApp and Telegram capability — 5 messages per month on each, enough to understand how the alerts work. Commercial use is allowed.
Best for: Developers who want to evaluate WhatsApp/Telegram alerting before upgrading, or who need commercial-use-allowed monitoring on a free plan.
The Real Question: What Matters to You?
| If you need... | Use... |
|---|---|
| Maximum free monitors | UptimeRobot (50, but personal use only) |
| Fastest free check interval | Better Stack (30 sec) |
| WhatsApp alerts on any plan | ndelog (5 free/mo, unlimited from $2/mo) |
| Commercial use, more monitor types | HetrixTools or ndelog |
| Telegram support | ndelog |
| SSL + domain monitoring free | HetrixTools or ndelog |
When to Pay
The free tier conversation is ultimately about: when does the limitation cost more than the plan?
Pay for WhatsApp alerts when your response time to downtime is constrained by whether you see an email or a WhatsApp. If you check WhatsApp before email in the morning — and most developers in ASEAN do — that's the threshold.
Pay for faster check intervals when 5 minutes of undetected downtime has a measurable business impact. For a client's e-commerce store, it does. For a personal blog, it doesn't.
Pay for commercial use explicitly allowed when you're a professional using monitoring as part of your service to paying clients. The risk of ToS violation on a free plan isn't worth the saving.
ndelog's Watchman plan at $2/month covers all three: unlimited WhatsApp, commercial use, and 60-second intervals.
→ Start with the free Spark plan — upgrade when you're ready